Known integrated gasification combined cycle (“IGCC”) power generation systems may include a gasification system that is integrated with at least one power producing turbine system. For example, known gasifiers may convert a mixture of a fuel such as coal with air or oxygen, steam, and other additives into an output of a partially combusted gas, typically referred to as synthesis gas or “syngas”. These hot partially combusted gases typically are scrubbed using conventional technologies to remove contaminates and then supplied to a combustor of a gas turbine engine. The gas turbine engine, in turn, powers a generator for the production of electrical power or to drive another type of load. Exhaust from the gas turbine engine may be supplied to a heat recovery steam generator so as to generate steam for a steam turbine. The power generated by the steam turbine also may drive an electrical generator or another type of load. Similar types of power generation systems may be known.
These known gasification systems generally require a conveying system to deliver a relatively steady flow rate of coal to the gasifier to ensure consistent performance. One known type of conveying system is a pneumatic conveying system in which finely ground particles of coal are conveyed through a conduit to the gasifier using a flow of gas such as nitrogen, carbon dioxide, or natural gas as the transport medium or carrier gas. The flow rate of coal, or any other type of conveyed solids in a pneumatic conveying system, however, generally may exhibit varying fluctuations. These solids flow rate fluctuations may be a result of a flow separation between the solids and the carrier gas that can be caused by elements of the pneumatic conveying system itself. For example, sharp bends or changes in cross sectional area of the conduit may cause disruption in the movement of the solids relative to the movement of the gas. Such may lead to some regions of carrier gas that are enriched in solids and other regions that are depleted in solids. In such circumstances, a plot versus time of the flow rate of solids past a fixed point along the conduit may take the shape of an irregular wave form with the peaks representing regions of solids enriched carrier gas and the troughs representing regions of solids depleted gas. Flow rate fluctuations may also be caused by other elements of a pneumatic conveying system such as the solids pressurization equipment. Such equipment, by its very nature, may cause aggregation or agglomeration of particles that can give rise to pulses in solids concentration downstream of the pressurization device. Such an unsteady flow rate, as described above, may lead to poor gasifier control and hence poor gasifier performance in the form of lower carbon conversions and the like.
There is thus a desire for an improved pneumatic conveying system. Such an improved pneumatic conveying system may provide a steady flow rate of solids, such as coal, which in turn may provide improved overall gasifier performance and, hence, improved power plant performance.